Image Guided Surgical Navigation
Image-guided systems are essentially like GPS (global positioning satellite) systems for the anatomy of your head. These systems are used to aid the surgeon in the confirming the location of critical structures when the interior of the nose and sinuses is distorted by unusual anatomy or prior surgery.
To use the image-guidance navigation system, a CT scan of the sinuses, is performed using a specific navigation system protocol. For some systems, a special mask or markers are placed on your face during the scan to serve as reference points. The CT scan is transferred to a disk, which is then loaded into the image-guidance computer.
During surgery, a detection array or a mask is placed on the patient’s head. The CT scan images loaded into the system are then calibrated to the patient’s anatomy using set pre-set reference points, which may be the mask or markers or specific anatomic points on the face. The position of the sinus surgery instruments can then be tracked by the computer by integrating the information detected from the patient’s pre-set reference points and comparing it to the information on the CT scan map.
When is image-guidance needed during sinus surgery?
Although the use of image-guidance systems is increasing in endoscopic sinus surgery, it is not required for all sinus procedures. Image-guided surgical navigation is not a substitute for sound surgical judgement and operative experience. Though it is tempting to demand its use during every surgery, it use does not make much of a difference in sinuses that have not been operated on before. Cases with straightforward anatomy also do not require image-guidance. Furthermore, when they are not indicated, the use of an image-guidance system unnecessarily adds to the length of the procedure and possibly the cost of the procedure.
Image-guidance is most useful while operating on patients who have had previous sinus surgery, patients who have more complicated anatomy of the frontal or sphenoid sinuses, cases of benign tumor growths such as inverted papilloma, and patients who have thinning of the bone between the sinuses and the brain or the eye. If the site of a cerebrospinal fluid (CSF) leak is identified on a preoperative CT scan, the image-guidance system may also be useful during CSF leak repairs to help is isolating the bony defect to be patched. In some cases in which both bony and soft-tissue detail is important, a special technology to merge CT scans, which provide good bony detail, and MRI, which offers better soft tissue detail can be merged to take advantage of both views during the surgery.